You are reading more into his statement that is there. Carrying the package under his arm does not preclude the top end sticking up above his shoulder. Frazier was non-specific about what parts of the package you could or couldn't see.
You do understand that if the bag contained a broken down rifle and the package was held by Oswald in the cup of his hand, the top of the package would have reached higher than Oswald's head?
Frazier said he couldn't see "much of the package". Go figure...
The desperate way that you try to exclude Frazier's statements is a clear indication that you already know that you've lost the argument. Now all you need to do is accept it!